Improvement in marine-propellers



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8 a I F a M INVEN T0 n;

WITNESSES:

YHE GRAPHIC c0. FHoTo-LlTH,39& kl PARK PLAOEJLY.

To all whom it may concern:

Be it known that I, FRANK G. FOWLER, of; Bridgeport, in the county ofFairfield andj State of Connecticut, have invented a new and UNITEDSTATES? FRANK e. rowLnR, or BRIDGEPORT, oomvnorrcur.

IMPROVEMENT IN MARlNE-PROPELLERS.

Specification forming part of Letters Patent No. i l 53,899, datedAugust 11,1874; application filed October 4, 1873.

Improved Marine-Propeller; .and I do hereby declare that the followingis a full and exact description thereof, reference being hadto the jaccompanying drawings, and letters of reference marked thereon, making apart of this specification, in which-1 Figure l is a side elevation ofmy invention. Fig. 2 is a plan view of the same with, .rudder and sleeveremoved. Fig. 3 is a plan view with cam removed, and also gives thedifferent positions assumed by the blades when the propeller is inmotion. Figs. 4 and .5 are side elevations of improved blades. 1 Fig. 6is a vertical longitudinal section of my improved cam. Fig. 7 is a planview of my improved step."

parts.

This lnventlon relates to improvements in submerged marine-propellersmounted on ver- .tical shafts and having feathering blades. In otherpropellers, in which the feathering motion is produced by an eccentric,there is a loss of power from the fact that the required angle of theblades essential to perfect propulsion cannot be obtained, the bladeshaving too coarse an angle at some points of their circuit and too fineat others, whereby a drag is produced and this'invention consists,first, in the employment of a cam-groove, trucks, connecting-bars, &c.,whereby any required .angle can be given them at any point of theircircuit, whereby perfect propulsion is produced. In other propellers thearms are attached to the blades at their extremities, two arms beingused for the same blade and this invention" consists, second, in an.improved blade, in which the arm is attached to the center of the blade,a single arm being used, whereby the resistance of an extra arm issaved, and the efficiency of the wheel greatly increased. In otherpropellers the'blades are rectangular in form, having perpendicular.

cutting-edges. These features are objectionable, for the reason that aperpendicular or parallel cutting-edge does not enter or divide Similarletters of reference indicate like;

the water so readily as a diagonal cuttingedge; and as the blade passesthe stern-post it strikes the dead water simultaneously throughout itsentire length, by which a severe shock is produced; and this inventionmay be constructed with blade having a convex cutting-edge and a concavefollowingedge. By having the cutting-edge circular it passes through thewater with far less resistance, thereby economizing a great amount ofpower, and in passing through the dead; water at the stern-post itenters it so gradually that'no shock is produced. This form of bladepossesses other advantages. As the forward portion comes in contact withthe water, which is thrown off by the pressure of the blade, it againcomes in contact with their diagonallyextending extremities, by whichthe blades obtain a more stable fulcrum than if they were rectangular inform. Other propellers operating in salt water, if constructed of iron,are liable to be corroded and destroyed by the action of salt water; andin forming the journals or bearings of such submerged propellers, it isnecessary that they should be run on lignumvitze, and for this purposeit is necessary to employ brass or copper to run in contact with thelignumvitee, for, if iron is used, it soon becomes rough by corrosion,and wears or rasps the lignumvitze rapidly away; and

in so employing brass it greatly aggravates the corrosion of the ironabove referred to, as a galvanic action takes place between the iron andbrass; and this invention consists, third, in casting the eccentric orcam with a .recess, and filling the same with zinc, and in attaching abox or boxes containing zinc or other analogous material to the step ofthe propeller, whereby the corrosive and galvanic action is neutralized,and the iron preserved, as the corrosive and galvanic action of seawater will now be directed to the zinc, it being more easily oxidizedthan iron.

The steering qualities of my propeller may be improved, by attachinga-rudder to 1.11116 sleeve of the propeller, whereby it can be op eratedwith the same helm that serves to steer the boat when steaming, and bywhich means the boat can be steered when under sail, whereas in otherpropellers, if a rudder is em PATENT OFFICE.

and a blades attached to the arms by a piv-.

oted joint. 70 is a horizontal cam, attached, by suitable connections,to the helm H. It is traversed by the trucks It, being provided for'thatpurpose with the groove is. These trucks are all sustained by the pivotor bearing at the extremity of the rod c. This rod is connected,'by apivot at its outer extremity, to the blade to, and at its innerextremity is held in position by the short connecting-bar o. This bar isattached at one end to the rod 0', and at the other, by a pivot, to themain arm of the propeller, the arrangement being such that, as thepropeller revolves, the trucks will traverse the groove of the cam,giving a vibrating motion to the bar 1;, a reciprocating motion to therod 6', and an oscillating motion to the blade 0.. That will cause theblades to exert a propelling force throughout their entire circuitexcept when passing two dead-points m and n. The manner in which thegroove of the cam is laid off so as to secure a proper angle of theblades, and insure the blades propelling with equal speed throughout anentire revolution, will be understood by reference to Fig. 3. Take, forexample, a blade at the point P. Let the dot line A be drawn in thedirection of the thrust of the propeller or of the line of the vesselsprogress, and the line T be drawn tangent to the propeller. The line Cwill represent, the position of the blades. We shall then have atriangle in which the base is a tangent line; the altitude, the line ofthe vessels progress; and the hypotenuse, the line of the blades. If theline T be made to represent the circumference of the propeller, the lineA will represent its pitch, and the line C the cycloidal curve that theblade describes when the vessel is under way. The lengths of the linesin the case referred to will be represented by the numbers 10, 5, and11. Therefore, if the circumference of the propeller is ten feet, thepitch will be five feet and the cycloidal curve eleven feet. But that istrue of the blade, so

far as the cycloidal curve is concerned, only in passing that point, andrepresents an instantaneous compensation; but the pitch must be acertain component part of the circumference at all times, and the line Ais seen to be one-half the length of the line T throughout an entirerevolution.

v From the foregoing it will be seen that to properly lay off the grooveof the cam it is only necessary that it shall be such that the bladewill be held in such a position that the line A will always be a certaincomponent part of the line T when the blades will be propelling with thesame speed throughout their entire circuit; but if the blades arefeathered with an eccentric the line A will sometimes be longer andsometimes shorter than the line T, in which case the pitch of the bladesor their speed of propulsion difier correspondingly, which results in a'great loss of power.

My improved single-arm blade will be understood by reference to Fig. 4,which represents a blade with a single attachment for the arm, and thatis in the center of the blade. No undue strain is brought to bear on thepivot, as the pressure on the upper half of the blade balances thepressure on the lower half.

An improved form of blade is represented by Figs. 4 and 5, the latterrepresenting a blade with attachments for two arms. By having thecutting-edge convex it enters the water more readily, it being partiallydrawn instead of being pushed directly forward; and by having thefollowing-edge concave the proper width of the blade is preserved, andby the general configuration which results the bladeeis rendered a moreeflicient propelling instrument; but the edges need not, necessarily, beconvex and concave, but may be formed by diagonally extending straightlines for the cutting and following edges, with horizontal lines for theends, and would be represented by two rhomboids with their bases joinedtogether.

My device for the prevention of galvanic action and corrosion will beunderstood by reference to Figs. 6 and 7. It consists of a box attachedto the step of the propeller and filled with zinc-scrap, and is sodisposed before and after the shaft as to provide an ample receptaclefor the zinc without producing any additional resistance in the water. Asimilar box may be attached to the sleeve above the propeller. Theefi'ect of the zinc is to render the water antigalvanic and prevent thecorrosion of the parts of the wheel composed of iron.

A method for improving the steering qualities of such propellersconsists in attaching a rudder to' the sleeve of the propeller, and canbe used to steer the boat when the engine is not in motion or when theboat is under sail.

What I claim as new and useful, and wish to secure by Letters Patent,is-

1. The combination of means herein described, consisting of the arms aand e and cam 70, whereby the blade a is given cer= tain required anglesat different points in its revolution, as described and shown in Figs. 2and 3.

2. The vertically-arranged oscillating blade at, pivoted to, andsupported and operated by, the radial revolving arms a, substantially asdescribed and shown in Figs. 1 and 4.

3. Forming a blade with a convex cuttingedge and a concavefollowing-edge, in the manner and for the purpose as shown anddescribed.

4. The combination of an iron propeller with receptacles containing zincor other analogous material, whereby the destruction of the partscomposed of iron by corrosion or galvanic action is prevented WibhOllUadding to the bulk or resisting area of the propeller, as hereindescribed and shown in Figs. 6 and 7.

FRANK G. FOWLER.

Witnesses:

W. S. EDWARDS, D. A. TARBELL.

